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ADJUSTMENTS
MODEL
8559A
ADJUSTMENTS
5
-
26. SECOND CONVERTER ADJUSTMENTS (Cont'd)
The requirements for the converter response are illustrated in Figure 5
-
13a and are as follows: Bandpass
should be at least 17
MHz,
1 dB down. Amplitude of response at 3.75 divisions to the left and 3.75
divisions to the right of center screen should be as near the same as possible. These are the positions of the
IF signals for regular and alternate IE This is illustrated in composite photo Figure 5
-
13b. These positions
should be the same distance from the roll
-
off point at each end of the response curve.
Distance from roll
-
off points can be checked by centering signal with function generator disconnected then
reconnecting function generator and switching ALT IF on and off. This is illustrated in Figure
5-13c and 5-
13d.
Adjust
ASZ1, 22,
23
and L2 to satisfy the requirements of the converter response. If entire converter has
been replaced, try adjusting
ASZl and L2 first. Do not adjust A2 and A3 unless it is necessary to meet
requirements. Do not sacrifice amplitude to achieve flatness.
When adjustment is complete, disconnect function generator from
ASA2TP1, center signal on display,
and turn ALT IF on and off while monitoring signal.
Amplitude difference between regular and alternate IF should be no more than
0.4
dB.